Agilent Retention Time Locking with the MSD Productivity ChemStation Manual
Contents
1. os vi Agilent Technologies desired match in retention times To lock a given method for the first time or for the reasons above you must first develop a Retention Time vs Pressure RT vs P calibration curve Using an established method multiple five injections of the standard are used to calculate the reten tion times at predefined inlet pressures The use of an auto matic sampler simplifies this process The RT vs P calibration data for each of the five injec tions are saved and used to cor rect locked methods The five defined pressures are e Target pressure 20 e Target pressure 10 e Target pressure nominal method pressure e Target pressure 10 e Target pressure 20 Even when using columns with the same part number same id stationary phase type phase ratio and same nominal length separate and different locking calibration curves may be needed Other examples of when separate locking calibration curves are required include e Systems with different column outlet pressures MSD vacuum FID atmos pheric e Columns differing from the nominal length by more than 15 for example due to trimming e Systems where the predicted locking pressure falls outside the range of the current cali bration Selecting the Standard Compound for RTLocking A specific compound usually one found in the normal method calibration standard must be chosen and then used for both developing2. fa Enhanced Data Analysis RTLPESTB M 7 RTLOCK3 D MS Data Not Quantitated ra 2 TIC RTLOCK3 D EasylD Edt Gtent Result Edition tene Peaks Parametric Retrieval Align GC Review Peak Purity Results Screener RTLock Setup Enter RT Locking setup mode Figure 11 To define a new compound for RTLocking select RTLock Setup from the View menu in data analysis After selecting the compound to RTLock from the RTLock menu item select Calculate New Curve from Selected Peaks This will generate a new RT vs P cali bration curve The new RT vs P calibration curve equation will be displayed on the screen along with the correlation coefficient Select Yes to create a new or update an existing RTLock cali bration See Figure 12 From the RTLock menu you can also e View current setpoints e Calculate the RT vs P curve e Restore the original chromatograms e Report the RTLock calibration Unlock the method e Relock the method te Enhanced RTL setup RTLPESTB M is LOCKED jee View Help View Current Method Setpoints Calculate New Curve from Selected Peaks Restore Nominal Chromatogram Report RTLock Calibration Print Relock Method Unlock Method e 10 00 Figure 12 RTLock view and menu choices www agilent com chem Summary RTLocking provides an easy and flexible tool that can be used to reduce the time and complexity often associated with routine chromatogr
3. the locking calibra tion and locking all future sys tems The compound or target peak should be easily identifi able symmetrical and should elute in the most critical part of the chromatogram Compounds that are very polar or subject to degradation should be avoided Once the target compound has been chosen and all other chro matographic parameters of the method have been determined the five calibration runs are per formed The resulting RT vs P calibration curve data are saved The software is then used to select and integrate the peak used for locking Creating an RTL Method The following is an overview of the actual steps taken to acquire the RT vs P calibration curve data selecting the compound peak to use and locking the method Acquiring the RTLock Data From Instrument Control select the Instrument menu and MA GC MS Instrument 1 DEFAULT M Acquire RTLock Calibration Data Agilent Technologies GCs are the only ones supported See Figure 1 If you are using an automatic sampler the five sample injec tions will be made automatically This example illustrates how RTL works on a GC MS system Upon completion of the five sample analysis Data Analysis will begin and display the nomi nal MS total ion chromatogram TIC If the system was config ured as a stand alone GC all five chromatograms will be dis played From these displays you will select the compound that will be used for RTLo
4. you can analyze and process new samples This requires that you unlock and relock the methods without editing the quantitation calibration data The following example demonstrates how retention times might change when column maintenance is performed or a method is moved to anew GC MS system See Figure 9 Once the method is RTLocked new samples are ana lyzed and retention times cor rected See Figure 10 Unlocking and Relocking a Method Once a method is locked you may unlock or relock it using the same or different compounds or after additional maintenance To define a new compound for RTLocking select RTLock Setup from the View menu in Data Analysis See Figure 11 The nominal RTLock sample that rep resents the method you are work ing on will be displayed Once again use the mouse to identify a new RTLock compound FE window 2 Abundance After cut 400000 J Locked y T_T TIC RTLAFTER D TIC RTLOCK D 300000 200000 100000 0 Time gt 14 00 16 00 18 00 Figure 9 Overlay of an RTLocked data file labeled Locked and the resulting data file after clipping one meter off the column labeled After Cut FE window 2 Abundance BD TERT TIC RTLPOBST D 400000 300000 200000 100000 0 Time gt 16 00 18 00 Figure 10 Offset overlay of RTLocked data file and the RTCorrected datafile show peaks overlapped and corrected for column maintainence
5. Retention Time Locking with the MSD Productivity ChemStation e e eo o l l c 0 e e Technical Overview a o Oe e e e Introduction A retention time is the fundamental qualitative measurement of chromatography Most peak identi fication is performed by comparing the retention time of the unknown peak to that of a standard It is much easier to identify peaks and validate meth ods if there is no variation in the retention time of each analyte However shifts in retention time occur frequently Routine maintenance procedures such as column trimming alter retention times In a multi instru ment laboratory running duplicate methods the retention times for each instrument will differ from each other even when run under nominally identi cal conditions These differences in retention times mean that each instrument must have a separate calibration and integration event table making it time consuming to transfer methods from one instrument to another Differences in retention time also complicate comparison of data between instruments over time What Is Retention Time Locking Retention time locking RTL allows a close match of retention times on one Agilent Technologies GC MSD or GC system to those on another like system with the same nominal column By making an adjustment to the inlet pressure the retention times on one system can be closely matched to those on another system using the same nominal c
6. ame acquisition date instrument name and operator name e Report date Multi u F HPCHEM 1 METHODS RTLPESTB M RTLREP TXT olx B Fie Edit Search Window Retention Time Locking Data Report Retention Locked Method Retention Locked Cal Date 11 May 1998 Instrument GC MS Ins Operator Method Lock is currently On Compound Chloropyrifos methyl Retention Time Calibration psi Time File Pressure min RTLOCK1 D 12 66 17 345 RTLOCK2 D 14 24 16 940 RTLOCK3 D 15 82 16 567 RTLOCK4 D 17 40 16 214 RTLOCKS D 18 98 15 885 Maximum Deviation RTL Curve R Terms of Curve Fit Constant 1 35686e 007 Linear 1 20506e 006 Quadratic 27275 2 Coefficient Locked Retention Time informati Retention Locked File Acq Date Instrument Operator Spec Xcor 000 000 000 000 000 Herer 46 650 seconds 2 73e 004 A A 1 21e 006 A 1 36e 007 on la x F HPCHEMS 1 METHODS RTLPESTB H 7 35 pm Deviation Seconds 46 650 22 356 0 000 21 192 40 968 0 999997 Good Fit HP Demo RTLOCK3 D 11 May 1998 HP Demo 7 35 pm Measured Retention Time 16 567 Pressure 15 82 psi Locked Retention Time 16 596 Pressure 15 69 psi Locked RT and Pressure Within Calibrated Limits Leck run spectrum XCor 1 0000 Report created Wed Sep 23 15 35 55 1998 Figure 8 Example RTLock Report Running an RTLock Method Once the RTL method is created
7. aphic maintenance It allows methods to be trans ferred between like GC MS sys tems without time intensive edits to the quant database and reacquisition of standards It also simplifies the process for executing routine chromato graphic maintenance RTLocking can minimize mistakes and pro vide a productivity improvement for most applications by reduc ing the time and setpoint changes required to update a method For More Information For more information on our products and services visit our Web site at www agilent com chem Agilent shall not be liable for errors contained herein or for incidental or consequential damages in connection with the furnishing performance or use of this material Information descriptions and specifications in this publication are subject to change without notice Agilent Technologies Inc 2008 Printed in the USA May 5 2008 5989 8574EN a Agilent Technologies
8. cking of the method Selecting the RTLock Compound Use the mouse to select the com pound or peak that you would like used for locking For GC only mode you must select one peak from each of the five chro matograms for RTLocking Once you have made your selection you will be asked to allow the software to automatically find the remaining peaks You may choose to zoom the display for better visibility See Figure 2 Method BUS iitiia View Abort Window Qualify Help Run Time Inlet Injection Types g GC Edit Parameters Z GCP E GC Monitors Detectors Select MS Tune File Y MS SIM Scan MS Monitors inje Edit MS Tune Parameters Perform MS Autotune ane Figure 1 GC Status Messages Total lon Volts zai Temperature eae Flow Cal EEN From instrument control you select the mode of data acquisition for RTL E Enhanced RTL setup RTLPESTB M is LOCKED eA 12 TIC RTLOCK3 D OOL 144155 168180 197 212 228 243 258 271 50 100 150 200 250 300 Click Drag RIGHT Mouse under desired Peak for Lock Calculations Figure 2 From this panel the user selects the peak used for RTL In this example the second peak has been selected The spectrum of the selected compound is also displayed and is used to confirm the RTL compound E En
9. hanced RTL setup RTLPESTB M is LOCKED lO x BTLock View Help E window 2 miei pues TIC RTLOCK1 D 1945 i T 3 T T T T AEROS T T T l T T T T T Time gt 10 00 20 00 30 00 remane TIC RTLOCK2 D 1945 f XCR 0 999681 Time gt 10 00 20 00 30 00 Pounceies Nominal T C RTLOCK3 D 1945 i T i T T T T ZER T T T T T T T T T Time gt 10 00 20 00 30 00 fae TIC RTLOCK4 D X CR 0 999909 1945 i T A T T T T T T T L T T T T T Time gt 10 00 20 00 30 00 Abundance TIC RTLOCKS D 1945 Bi XCR 0 9996 l Time gt 10 00 20 00 30 00 96 308 321 300 Figure 3 When the RT vs P calibration curve equation is calculated the correlation coefficient is determined for the RTLocked compound in each of the five calibration samples The resulting coefficient is displayed at each peak The nominal or no change to pressure calibration sample has a correlation of 1 Calculating the RTLock Curve and Saving a Method Once the RTLock compound has been selected the new RT vs P curve for each compound will be displayed To select a new com pound and calculate new RT vs P curves reset the nominal MSTIC from the RTLock menu item Select a new compound as the RTL compound and from the RTLock menu item select Calcu late New Curve from Selected Peaks This will generate new RT vs P calibration curves The new RT vs P calibration curve equa tion will be displayed on the scree
10. n along with the correlation coefficient Select Yes to either create a new or update an exist ing RT vs P calibration file See Figure 3 Next you can enter the name and retention time of the RTLock compound See Figure 4 and Figure 5 OK Cancel 0 9 Figure 4 Enter or confirm the name of the RTLock compound TIC RTLOCKS D Figure 5 Enter or confirm the retention time of the RTLock compound You will then be asked to con firm the RTLock pressure that has been calculated and will be used for that method Select Yes to confirm the new RTLock pressure and save the method See Figure 6 TIC RTLOCK5 D Figure 6 By selecting Yes you RTLock and save the method View Current RTLock Method Set points and Report Once the system is calibrated and locked you can view and confirm the RTLock setpoints by selecting View Current Method Setpoints See Figure 7 A Le Figure 7 Viewing the RTLock retention times and corresponding pressures for the RTLock method A report is also available that provides detailed information regarding the RTLock method See Figure 8 The report includes Method name e Calibration date e Instrument name e Operator name e Status of method on or off RTLock compound name Tabular retention time pressure calibration table Maximum deviation RTLock curve equation and correlation coefficient data Locked retention time infor mation file n
11. olumn The ability to very closely match retention times from one system to another can greatly reduce the time it takes to develop and transfer methods RTLocked methods can also compen sate for degradations in chromatographic perfor mance The ability to correct for degrading chro matographic performance optimize lab resources and still provide the correct answer saves time money and results in significant productivity gains Using GC MS it is also possible to screen samples for the presence of target compounds using a mass spectral database of RTL spectra The RTL mass spectral database provides additional confirma tory information in spite of changes to the chro matographic system One such database is the G1672AA Pesticide RTL Library This database allows for quick and easy screening of pesticide samples When Should I Lock My Methods Locking or relocking your methods should be done whenever you make any changes to the chromato graphic system or move methods from one system to another GC or GC MS To establish and main tain a locked method RTL should be performed whenever The column is changed or trimmed The method is installed on a new instrument A detector of different outlet pressure is used GC vs MS System performance is validated Troubleshooting chromatographic problems How Does It Work The process of RTL is to determine what adjust ment in inlet pressure is necessary to achieve the
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Agilent Retention Time Locking with the MSD Productivity ChemStation Manual